HVSR and MASW seismic survey for characterizing the local seismic response: A case study in Catania area (Italy)

Many recent researches show that the site seismic response is strongly influenced by stratigraphic and topographic features. Site response can reduce or amplify the earthquake induced ground motion. An integrated approach based on passive (HVSR) and active (MASW) seismic surveys, was carried out at the Garibaldi Hospital, located in Catania downtown, in order to evaluate the seismic site response. Fourteen environmental noise records, located near some previously mechanical drillings, were carried out and processed by using the Horizontal to Vertical Spectral Ratio (HVSR) technique. Successively, two MASW prospections were performed at the northern and the southern sides of the Hospital building, following the information deduced from the stratigraphic characteristics of soil drillings. The data obtained from this coupled analysis, method and the information derived by mechanical drillings previously performed, allowed us to obtain the site transfer function which can be related to the H/V average spectrum. Such integrated approach, based on passive and active seismic prospections, showed to be a reliable and quick method to obtain information for a site seismic characterization. According to Italian code a Vs30 profile was achieved and the soil type category was determined

Comparison of in situ devices for the assessment of pavement subgrade stiffness

The subgrade is the top surface of a roadbed upon which the pavement structure is constructed. The purpose is to provide a platform for construction of the pavement and to support the pavement without unwanted deflection that would reduce its performance. For those reasons subgrade bearing capacity have to be investigate during the construction process as a quality control, based on the design results. The dynamic in situ Falling Weight Deflectometer (FWD) tests are nowadays widely used and considered the most reliable and suitable approach to determine bearing capacity of road pavements and elastic moduli. In addition, the use of the Light Weight Deflectometer (LWD) takes the advantage of the dynamic application of load, and the flexibility of the handling of the equipment on construction area and unbound layer. In the present paper, a wide literature review is presented on the topic of correlation between different subgrade bearing capacity in situ tests. In order to assess the transferability of LWD measures, these results were compared with FWD test and Dynamic Cone Penetrometer (DCP) test. Soil samples, taken from the site, have also been investigate in laboratory to relate geotechnical and in situ test results

Proprietà dinamiche dei terreni del centro storico di sellano attraverso prove di RCT CLTST e DSDSS

Nella presente nota sono riportati i risultati di prove di laboratorio dinamiche (colonna risonante) e cicliche (taglio torsionale e taglio semplice) per la misurazione della rigidezza e dello smorzamento dei campioni di terreno prelevati nel centro abitato di Sellano (Pg), colpito dal terremoto Umbro Marchigiano del 1997. I risultati sperimentali sono espressi in termini di modulo di taglio massimo (Gmax), modulo di taglio normalizzato (Gs/Gmax) e di fattore di smorzamento (D)

Geotechnical seismic hazard evaluation at sellano (Umbria, Italy) using the GIS technique

A tool that has been widely-used in civil engineering in recent years is the geographic information system (GIS) [1]. Geographic Information systems (GIS) are powerful tools for organizing, analyzing, and presenting spatial data. The GIS can be used by geotechnical engineers to aid preliminary assessment through to the final geotechnical design. The aim of this work is to provide some indications for the use of the GIS technique in the field of seismic geotechnical engineering, particularly as regards the problems of seismic hazard zonation maps. The study area is the village of Sellano located in the Umbrian Apennines in central Italy, about 45 km east of Perugia and 120 km north-east of Rome The increasing importance attributed to microzonation derives from the spatial variability of ground motion due to particular local conditions. The use of GIS tools can lead to an early identification of potential barriers to project completion during the design process that may help avoid later costly redesign. © 2008 American Institute of Physics

Geotechnical characterization of ash collected during recent eruptions of Mount Etna: from dangerous waste material to environmental friendly resource

An exponential increase in the activity of Mount Etna (Catania, Italy) has been observed between the massive eruptions that lasted from 1991 to 1993 and the very significant ones, which occurred between 2012 and 2018. Large amounts of ash repeatedly covered the city of Catania, causing environmental problems for road and air traffic, agriculture and human health. Recent thinking has been to consider volcanic ash as a resource rather than a waste material, thus avoiding damage to both the environment and human health. This goal could be achieved using this material in several fields of geotechnical engineering but first static and dynamic laboratory geotechnical tests must be performed. This paper deals with a static and dynamic geotechnical characterization of volcanic ash collected during recent eruptive activity on Mount Etna. Grading and index properties tests, oedometer tests, direct shear tests and dynamic resonant column tests were performed in the Geotechnical Laboratory at the University of Catania. Particle crushing was also analysed following oedometer tests and direct shear tests. The tested materials are essentially of a gravelly-sandy nature and showed very different strains due to the different grain size distribution curves as well as to the aptitude to crushing of these materials. Cohesion is negligible both at peak state and at the critical state, in line with granular soil behaviour. A light curvature of the failure curves can be observed for some peak envelopes. The results of dynamic tests are in quite good agreement with those of well-known sands. Thus, taking into account crushing, it is possible to appropriately reuse these materials in geotechnical engineering avoiding inhalation and ingestio

A procedure for the evaluation of geotechnical risk in urban areas: The case of Centuripe town

In Italy, many urban areas suffer geotechnical hazard problems. However the Municipalities are not yet organised either to deal with the consequences of the possible phenomena, or to plan risk factor mitigation actions, by vulnerability reduction of the exposed elements. Before acting, a deep knowledge of the studied area and of the most important element at risk is needed. For this aim, one of the most widely used procedures is microzonation. This follows the recommendations of the "Manual for zonation on areas susceptible to Rain-Induced Slope failure" (ATCGNH - ISSMFE (Asian Technical Committee on Geotechnology for Natural Hazards in ISSMFE) The Japanese Geotechnical Society, July, 1997), for example, compiling expressly designed penalty forms. In this work, an approach to detect the vulnerability factors of Centuripe town's (EN - central-eastern Sicily) historical centre buildings is shown. A model of the penalty form based on the one proposed by Massimino et al. (The Grade 2 microzonation of Sellano. Italian Geotechnical Journal, XXXV, n.4, pp. 79-89, 2001) and conveniently modified to point out hydrogeological risk (Raciti et al. "GIS Techniques Application in Geological Hazard of Slope Instability Map Editing". Mining and Environmental GeoEngineering, XLV, n. 1, April 2008) is proposed. The proposed forms will be compiled for 101 buildings and 3 roads. © 2009 WIT Press

Geotechnical seismic hazard evaluation at Siracusa (Sicily) using GIS techniques

Siracusa province is prone to seismic risk. Many towns of the Siracusa province were destroyed by the 1693 earthquake; among these, the town of Noto was completely destroyed and rebuilt in a site some kilometres distant from the original one. To evaluate seismic risk at a specific area, it is important to have as much information as possible about many data related to the given area, but there are several problems with detection, collection, and use of spatial data/information for disaster management. Seismic hazard can be related with the consequences for exposed buildings and human life. GIS technologies could play a crucial role in analysing large areas, but a good geodatabase should be designed and populated with all the available data. The research that is being carried out has the aim to obtain an approach to detect seismic hazard factors and vulnerability elements of urban areas. To evaluate seismic vulnerability, a geo-database in terms of conceptual, logical and physical model to collect and store information about multy-risk analyses have been created to point out especially seismic risk evaluation. To evaluate seismic hazard, some scenario earthquake of a studied area should be applied to calculate the site seismic response. In this work the studied area is Siracusa, one of the most beautiful town in Sicily (Italy), with a baroque old town centre built after the great 1693 earthquake that destroyed eastern Sicily. The level 1 “scenario” earthquake is that of 1693 with its synthetic accelerogram, while level 2 “scenario” earthquake is the most significant shock which occurred during the 1990 Sicily earthquake, recorded on rock at the accelerometric station located in the town of Sortino, near Siracusa. Based on the site characterization of Siracusa area, the soil response is analysed. For each different zone and for the input motions considered as “scenario” earthquakes the response spectra at the surface level is developed. Some examples of site response evaluation of Siracusa area is shown in this paper. Finally, a seismic geotechnical hazard map in terms of maximum horizontal acceleration at the soil surface is drawn-up

Seismic displacements of retaining walls: Shaking table test results vs numerical predictions

The seismic performance of retaining walls is usually evaluated through simplified displacement-based approaches which neglect the change in the soilwall system geometry as displacements develop. In this vein, the paper describes the results of several shaking table tests carried out on a reduced-scale model of a retaining wall placed inside a flexible soil container and subjected to harmonic input motions. In the paper the permanent displacements of the wall and of the retained soil were presented and compared with numerical predictions obtained using a modified Newmark-type model, which encompasses the kinematic compatibility between the wall and the soil

Soil Characterisation of Catania Harbour by the Seismic Dilatometer Marchetti Test (SDMT)

The city of Catania, located on the eastern zone of Sicily, is prone to high seismic risk. The Catania harbour is an important tourist, industrial and commercial harbour of Italy. For site characterisation of soil deep site investigations have been undertaken. Borings and Seismic Dilatometer Marchetti Tests (SDMT) have been performed, with the aim to evaluate the soil profile of shear waves velocity (Vs). Moreover the following laboratory tests were carried out on undisturbed samples retrieved with a 86 mm diameter Shelby sampler: Oedometer tests, direct shear tests, triaxial tests andresonant column tests. The available data enabled one to compare the shear waves velocity profile obtained by empirical correlations and Seismic Dilatometer Marchetti Tests(SDMT). The influence of strain level on G- and D- curves, as well as on shear strength, was evaluated by means of laboratory tests

Caratterizzazione geotecnica e amplificazione sismica nella zona industriale di Catania

Nel presente lavoro sono riportati i risultati relativi alla caratterizzazione statica e dinamica di un sito ricadente nell’area sismica della città di Catania. L’utilizzo di un’apparecchiatura di Colonna Risonante/Taglio Torsionale Ciclico ha permesso di ottenere risultati sul modulo di taglio G e sullo smorzamento D del terreno e di ricavare le leggi di degradazione di G e di incremento di D in funzione della variazione del livello di deformazione. Successivamente sulla base dei risultati ottenuti, si è proceduto, attraverso l’utilizzo di un modello di calcolo monodimensionale, alla valutazione dell’accelerogramma sintetico al bedrock, all’analisi della risposta sismica del terreno in superficie in funzione della storia temporale e dello spettro di risposta